This is a study of two cohorts of subjects. The first is a group of young (6-7 year old), attention deficit disorder (ADD) children and their controls. The second cohort is comprised of two groups of formerly ADD children, one group whose subjects were found on follow-up to have been arrested for serious offenses and the other group whose subjects had not been arrested in their teen years. The first study aim is to clarify the relationship between EEG, electrodermal amd event related potential (ERP) measures and the symptomatology of young, hyperactive, attention deficit disorder children. The second aim is to examine the scalp distribution (topographic maps from 16 electrode sites) of ERP and EEG data in these two groups of children. The third aim is to clarify and replicate electrophysiological differences which we previously found between two groups of formerly ADD children and a group of formerly normal children recently evaluated as part of a long term follow-up study. The three groups to be further studied are: 1) ADD youths who had been arrested more than once for a serious offense; 2) ADD youths who had not been arrested; 3) normal youths who had not been arrested. The fourth aim is to help clarify the relationship found previously between eosinophil counts, ERP components, and the behavioral measures within a group of ADD children and to validate the ADD-normal group differences in eosinophil count found previously in young children.